What is CVE-2021-47561?

CVE-2021-47561 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10, classified as a Use After Free flaw (CWE-416), affecting Linux kernel versions from 5.15 onward and patched in 5.15.6 and 5.16. CVE-2021-47561 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is the CVSS score for CVE-2021-47561?

CVE-2021-47561 has a CVSS score of 7.8 out of 10, rated High severity. The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.

Is there a patch available for CVE-2021-47561?

Yes, CVE-2021-47561 has been patched. Fixed versions include 5.15.6 and 5.16. If you are running Linux kernel 5.15 or later up to the fix versions, apply the relevant patch for your kernel branch.

Is CVE-2021-47561 actively exploited?

CVE-2021-47561 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

What is Use After Free (CWE-416)?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. See MITRE CWE for full details: https://cwe.mitre.org/data/definitions/416.html

CVE-2021-47561

High

In the Linux kernel, the following vulnerability has been resolved: i2c: virtio: disable timeout handling If a timeout is hit, it can result is incorrect data on the I2C bus and/or memory corruptions in the guest since the device can still be operating on the buffers it was given while the guest has freed them. Here is, for example, the start of a slub_debug splat which was triggered on the next transfer after one transfer was forced to timeout by setting a breakpoint in the backend (rust-vmm/vhost-device): BUG kmalloc-1k (Not tainted): Poison overwritten First byte 0x1 instead of 0x6b Allocated in virtio_i2c_xfer+0x65/0x35c age=350 cpu=0 pid=29 __kmalloc+0xc2/0x1c9 virtio_i2c_xfer+0x65/0x35c __i2c_transfer+0x429/0x57d i2c_transfer+0x115/0x134 i2cdev_ioctl_rdwr+0x16a/0x1de i2cdev_ioctl+0x247/0x2ed vfs_ioctl+0x21/0x30 sys_ioctl+0xb18/0xb41 Freed in virtio_i2c_xfer+0x32e/0x35c age=244 cpu=0 pid=29 kfree+0x1bd/0x1cc virtio_i2c_xfer+0x32e/0x35c __i2c_transfer+0x429/0x57d i2c_transfer+0x115/0x134 i2cdev_ioctl_rdwr+0x16a/0x1de i2cdev_ioctl+0x247/0x2ed vfs_ioctl+0x21/0x30 sys_ioctl+0xb18/0xb41 There is no simple fix for this (the driver would have to always create bounce buffers and hold on to them until the device eventually returns the buffers), so just disable the timeout support for now.

Package Linux Kernel

Published 2024-05-24

Last modified 2025-09-18

CVSS version 3.1

Patch available

Yes

CVSS 3.1 score

7.8

out of 10

High

Attack Vector

Local

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Vector string

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness type

CWE-416

CVE-2021-47561 is a Use After Free vulnerability

What is Use After Free?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. Learn more on MITRE CWE

Affected versions

Linux kernel versions 5.15 and later are affected. Fixed in 5.15.6, 5.16 and their respective stable series.

Affected from

≥ 5.15

Fixed in

✓ 5.15.6 5.15.x ✓ 5.16

References

2 total

Kernel Git
https://git.kernel.org/stable/c/84e1d0bf1d7121759622dabf8fbef4c99ad597c5

Patch
Kernel Git
https://git.kernel.org/stable/c/cc432b0727ce404cc13e8f6b5ce29f412c3f9f1f

Patch

Details

CVE ID CVE-2021-47561

Severity High

CVSS score 7.8 / 10

CVSS version 3.1

Published 2024-05-24

Modified 2025-09-18

KEV No

Patch

Yes

Package linux

Frequently asked questions

What is CVE-2021-47561?

CVE-2021-47561 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 5.15 onward and has been patched in 5.15.6 and 5.16. CVE-2021-47561 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.
What is the CVSS score for CVE-2021-47561?

CVE-2021-47561 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H.
Is there a patch available for CVE-2021-47561?

Yes. CVE-2021-47561 has been patched. Fixed versions include 5.15.6 and 5.16. If you are running Linux kernel 5.15 or later up to the fix versions, apply the relevant patch for your kernel branch.
Is CVE-2021-47561 actively exploited?

No. CVE-2021-47561 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.